What is C tag and S-tag?

C-Tag is an abbreviation of Customer VLAN tag. In this double tagging, the C-Tag (customer tag) is the inner tag set by the customer. The S-Tag is the outer tag next to the MAC address.

What is service VLAN and customer VLAN?

VLAN tunneling is an enhancement of the QinQ/Nested VLAN/Customer mode VLAN feature. It enables service providers to use a single VLAN to support customers who have multiple VLANs, while preserving customer VLAN IDs and keeping traffic in different customer VLANs segregated.

What is inner VLAN and outer VLAN?

Within an Ethernet Frame, these two tags are often known as “Inner tag” and “Outer tag”. “Inner tags” contain VLAN information that belong to the traffic of the NSP’s customers. The “Outer tags” contains information relating to the NSP’s VLAN networks.

What is S-tag in networking?

S-Tag is an abbreviation of Service VLAN tag. The IEEE standard 802.1ad provides for double-tagging by service providers so that they can use VLANs allocated internally together with traffic already tagged as VLANs by service provider customers. The standad 802.1ad specifies a TPID of 0x88a8 for the outer S-Tag.

What is QinQ tunneling?

A Q-in-Q VLAN tunnel enables a service provider to segregate the traffic of different customers in their infrastructure, while still giving the customer a full range of VLANs for their internal use by adding a second 802.1Q tag to an already tagged frame.

What VLAN ID should I use?

1. Type the VLAN ID provided by your ISP for the Internet VLAN ID. For example, DoDo NBN provides VLAN100 for Internet service, DoDo user should type 100 for Internet VLAN ID.

What is the difference between QinQ and Dot1q?

Dot1q termination: terminates packets that carry one VLAN tag. QinQ termination: terminates packets that carry two VLAN tags.

What is QinQ used for?

In Q-in-Q tunneling, as a packet travels from a customer VLAN (C-VLAN) to a service provider’s VLAN, a customer-specific 802.1Q tag is added to the packet. This additional tag is used to segregate traffic into service-provider-defined service VLANs (S-VLANs).

What is Ethernet VLAN?

A virtual LAN (VLAN) is any broadcast domain that is partitioned and isolated in a computer network at the data link layer (OSI layer 2). VLANs allow network administrators to group hosts together even if the hosts are not directly connected to the same network switch.

What is the difference between dot1q and QinQ?

Switchport mode dot1q-tunnel interface level command is used to configure interface carrying Q-in-Q frames. While configuring the Q-in-Q the MTU needs to be carefully addressed, as the frame coming from customer may already contain 1500 bytes and by implementing Q-in-Q adds additional 4 byte in the frame.